Youtube Theme Engine by BlueCookieWookie

Youtube Theme Engine allows you to tweak almost every aspect of the YouTube UI including colors, buttons, text, media, and more.



24 built-in dark, light, and high-contrast themes
18-channel custom palette editor with live color preview
Contrast checker for readable text
Automatic switching by system theme or a daily schedule
Different themes per page (Home, Watch, Shorts, Search, Music, and more)
Share and import palettes with theme codes

Layout & Typography

18 fonts plus text size, line height, and weight
Content width, video grid columns and spacing, sidebar width
Stacked Watch layout with related videos below the player
Rounded thumbnails, buttons, and panels, five avatar shapes
Custom scrollbar colors and width

Media & Player

Change thumbnail and video brightness, contrast, saturation, grayscale, opacity, etc.
Themed progress bar with adjustable thickness
Rounded player corners, theater width, cinema glow
Hide endscreens, watermarks, info cards, and annotations

Focus (40 toggles)

Zen mode for distraction-free watching
Hide Shorts, Playables, comments, related videos, live chat, home feed
Hide ads surfaces, merch shelves, and members-only cards
Hide view counts, upload dates, likes, badges, and thumbnail overlays
Hide completed or live videos, community posts, mixes, and playlists